Radio telephone system



June 27, 1933. H. M. PRUDEN ET AL RADIO TELEPHONE SYSTEM Filed Aug. 15, 1931 4 Sheets-Sheet 1 M Y 0 E My m PM W k Ht? 5 R mm w H. M. PRUDEN ET AL 1,915,332

RADIO TELEPHONE SYSTEM Filed Aug. 15, 1931 4 Sheets-Sheet 5 FIG. 3

H. M. PRUDEN 'WENTORS: c. c. TAYLOR Brim A TTORNEV June 1933- M. PRUDEN ET AL 8 RADIO TELEPHONE SYSTEM Filed Aug. 15, 1-951 4 Sheets-Sheet 4 a QALLWIIH" 3 T if? .1 EC g k 1. i1 111 g I? G)!" U r mu. PRUDEN ac n4 YLOR ATTORNEY cos it HAROLD Ii I; PE'ULDEN, 01E MAFLEWOOD, NEW JERSEY, AND CHARLES C. TAYLOR, OF

. FLU'SEING, NEW? YORK; SAID PBUDEN ASSIGNOR T0 BELL TELEPHONE LABORA- res ns; rnconronArnn-or new vroan, i s, A conroaArion or new 2031:, Ann slain rAYLeaAssiencn. o AMERICAN rnnarnonn AND TELEGRAPH COM- PANY, A 'conroniirionor new YORK nAiiio rnnnrnonn SYSTEM Application filed August'l5 1931. Serial No. 557,232.

This invention relates to circuit arrangements for connecting a wire telephone system to a radio system and more particularly to an arrangement whereby communication facilities may be provided between telephone exchange system. and two geographically separated points by'means of a. radio link.

An object of the invention is to selectively" transmit, by means of a single radio transmitter, to either oftwo distant radio stations, under automatic control effected by an operator at the telephone exchange.

' In accordance with-this object, therefore, a feature of the invention resides in sw1tcli-' cated in the face of the switchboard, one for I each of the distant points to be communicated with, and corresponding thereto. The talking contacts of these jacks are connected in multipleto the toll. line circuit connecting the exchange with the radio station. The, sleeve circuits of these 1acks are separate, however, and, depend ng upon which gaclt' the operator selects by plugging in her cord circuit, the switching means at the radiostation is caused to operate to switch the radio transmitter into connection with the antenna having the proper directional character istics to communicate with-the-desired distant station. v

A further feature of this invention resides in an indicating arrangement whereby the operator at the switchboardis apprised, by means of signaling-devices, when the switchoperation is completed to the desired antenna,the signal continuing as a positive indication of the connection of the antenna with the transmitter until .theswitchis again operated. r V

Still another feature resides in-switching means also controlled at the time the antenna switch is'operated to automaticallyassociate the corresponding receiving station with the line to the exchange and to connect the other receiver with an auxiliary monitoring circuit terminating at the switchboard-whereby an operator may listen in or monitor on the 1 receiver not connected to the two-way conversation circuit.

Theinvention will be understood from the following description when read in connection with the accompanying drawings, the

figures of which, if placed end to end so that the figure numbers read sequentially from left to right, represent one terminal of raidio telephone system embodying the invenion. I l .7 Fig. 1 shows the equipment at the radio transmitting and receiving stations; and

Figs. 2, 3 and t show the equipment at the telephone exchange terminal of the wire line extending between the radio stations and the telephone exchange which, for purposes of description, will be assumed to be in New York. v v

The equipment consisting of busy signals, jacks and lamp signals and the operators cord circuit C, at the right of the vertical brokenline A--B in Fig. 4, represents the equipment at'the regular toll operators posi-tion in the New York toll ofiice, and all other equipment shown on Figs. 2, '3 and t represents the equipment at what is known asthecontrol or technical operators position which may for convenience be located in the same building as the toll switchboard. The

various-antennae which are shown by the conventional symbol on the drawings are of two general types, one transmitting and the other receiving. These antennae may be of any suitable type, for example, the transmitting antennae may be of the type disclosed in British Patent 329,321, accepted May 13, 1930 and the receiving antennae of the type disclosed in United States Patent to Bruce, No. 1,813,1 i3, July 7, 1931.

It will also be assumed that one of the directive transmitting antennae is pointed or directed to transmit to Buenos Aires and the other directed to transmit to Rio de Janeiro.

It will be further assumed, for purposes of description, that the last conversation was l with Buenos Aires and, therefore, the antact.

tennze switch (Fig. 1) consisting of switch arms 1, 2 and 3 is in its left-hand position and certain relays are operated, as shown in the drawings. Also, the service lamp 4 at the operators position will be lighted. It may now be, assumed that the New York toll operator desires to establish communication witlrRio de Janeiro. She will, therefore, first make sure there is no plug in the Buenos Aires jack and will then insert the calling plug (JP of her cord circuit C in the jack 5 (Fig. 4) which is marked in some convenient manner to" indicate that its destination is Rio de Janeiro, whereupon relay 6 will operate in an obvious circuit which closes at its upper contacts an obvious energizing circuit for rela 7 7. When rela 7 o aerat'es it closes at its contacts 8-an obvious circuit to energize relay 9 which relay in operating locks up at itsright-hand contacts and connects positive battery, at its contacts 10, over the switch control conductor 11 to cause the positively polarized relay 12 (Fig. 1) to 0pcrate and the negatively polarized relay 127 to release, thereby completing a circuit for the operation of relay 13 which locks up at its right-hand contacts. Relay 13 in operating, closes at its contacts 17 a circuit to operate relay 18 which may be traced from battery, contacts 19 of relay 20 and contacts 17 of relay 13 and winding of relay 18 to ground. 'Relay 18 in operating closes the power circuit to operate motor 16. Relay 13 in operating also closes its contacts 14 to connect battery to the motor direction lead 15 to cause the motor 16 to rotate in tl1e proper direction to operate the antenna switch. Motor 16 now rotates the switch blades 1, 2 and 3 to the right as determined by the energized conductor 15, and when switch blade 3 engages its rght-hand contact an obvious circuit is completed to energize relay 20, which in operating locks at its left-hand con- The operation of relay opens its contacts 19, thereby releasing relay 18 and stopping the motor. Relay 20 operated also connects negative battery at its contacts 60 to signal control conductor'21 to indicate the position of the antenna switch. This negative battery causes positively polarized relay 132 to release and operates negatively polarized relay 22 (Fig. 2), which operates relay 23 which in turn locks up through its lefthand contacts and'connects ground through its right-hand-contacts over conductor 148 to operate relays 24, 25, 26, 27 and 28. Relay 24 operates busy signal 29 to indicate to any other operator that the circuit is being used. It alsotransfers operated busy signal 30 from battery at contacts 61 toconductor 31 which .is'connected to battery by relay 43 which operates at this time in a manner to be de scribed later,,thereby keeping signal 30 operated. Relay operated connects 32 to lamp 33, and removes its connection from lamp 34. Conductor '35 is transferred from lamp 4 to lamp 36. Ground on conductor 37, at contacts 38 of relay 9, is connected to relay 39 which operates in an obvious circuit.

When relay 9 first operated it opened its contacts 40,'thereby releasing relay 39, which relay, however, is reoperated when relay 25 closes its front contacts. When relay 26 operates, battery through contacts 41 of relay 7 is connected to relay 42 which operates and closes an obvious circuit for relay 43. Relay 43 operates and opens the normally closed circuit for the bridged ringing relay 44 and connects battery to conductor 31, to hold busy signal operated. Busy signals 29 and 30 are now operated, thereby indicating to the operators that the circuit is in use. Also, the service lamp 36is lighted thus indicating to the operator that the antenna switch has been operated and the transmitter is connected to the Rio de 'Janeiro antenna.

When relay 27 (Fig. 2) operated the transmission line from the Buenos Aires receiver 150 was transferred from conductors 151 and 152 to conductors 46 and 47, which conductors continue through contacts of relay 48, privacy device 49 and contacts of relays 50 and 51 to monitoring jack 52 at the'switchboard and also through the bridged transformer 53 to ack 54 at the control operators position. Relay 27 operated also transfers the transmission line fromthe Rio de Janciro radio receiver 155 from conductors 46 and 47 to conductors 151 and 152 and thence over contacts of relays 56 and 62 through privacy 1 guishes lamp 58 and lights lamp 59. Relay '28 operated also transfers privacy control conductor 68 from conductor 69 to conductor 70 and privacy control conductor 71 from conductor 70 to conductor 69. The operator is now in direct, connection with the transmitting station and with the Rio do Janeiro receiving station'and is ready to ring the Rio de Janeiro operator, which she accomplishes in theusual manner by operating the ringing key BK in her cord circuit which operates relay 72 overa circuit which may be traced over'the tip and ring conductors of plug GP, jack 5, contacts of key 73, contacts of jack74, back contacts of relay 75 and winding of ring-up relay 72. Relay 72 operates, connects ground over contacts of jack 76 and through the windings of relays 77 and 78 to battery, which relays operate. Relay 72 operated also operates relay 79 in an obvious circuit. Relay 77 operated operates relays 80, 81 and 82. Relay 78 operated opens the transmission circuit and terminates each end in terminating resistances 83 and 84. Relay 79 operated connects 1000 cycle signalmg current, over contacts of jack 76 and the determined value. Relay 82 operated operates relays 62 and 64 in anobvious circuit and lights lamp 96wh1chserves to inchcate to the control operator that the Rio de Janeiro privacy circuit has been'removed, which,however, only remains lighted during the ring interval. Relays 62 and 64 operated transfer I the line normally extending through the privacy device 63 through compensating resistances 97 and 98.

Bridged across the line LT ahead of the delay circuit 86, is a detector amplifier 88 which detects and amplifies a portion of the ringing current which is passed along over the contacts of' relay 89 to operate relays 56, 57, (Strand 90. .Relay 56 operated opens the circuit LRR from the'ltio de Janeiro radio receiver. Relay 65 operated opens the line LR-to the receiving delay circuit 66 and detector amplifier 67. Relay 57 operated closes its contacts to connect the line LT over conductors 91 and 92 to the contacts 93 and 94 of relay 62 and through compensating resistances 97 and 98 and contacts 99 and 100 ofrelay 64 to conductors 101 and 102 and closed contacts of relay 90 to the transmitting line LTT. This ringing current now passes through the amplifier 103 to the transmitting station 104, where it operates certain apparatus, not shown, to send a'signal over the radio circuit to the receiving station at; Rio de Janeiro. When theoperator releases her ringing key BK, relay 72 releases and all relays operated by this'relay are restored tonormal. When the Rio de J aneiro operator answers her, voice signals will be re ceived on the recelv'lnggantenna 105 and.

translated in the receiver 155 and applied to the line LRRwhich extends through the amplifier 106, operated contacts of relay 27, contacts of relays 56 and 62 through the privacy device 63, 'normalconta cts ofrelays 64 and 65, delay circuit 66, amplifierl-O'l', loss control circuit 108, amplifier'109, hybridlcoil 7 80 and thence over the tip and ring of the two-wire line to the operators jack and cord circuit. Bridged across the 11119' aheadof delay circuit 66 is a detector 67 Wl'llOh detects and amplifies a small portionof the:

received voice signals sufiicient to operate sensitive relay 89. c This relay in operating opens its contacts to prevent any false operation of relays controlled by detector amplilier 88 bridged across the transmitting line LT during receipt of incoming speech currents. When the incoming speech currents cease relay 89 releases andrecloses its contacts. When voice currents. are transmitted Relay 81 operated adjusts the transmission loss for control 95 to a pre-' by the-operator at the exchange, these signals cause the operation of detector amp1iher '88 which operates relays 56, 57, 65 and 90 to connect the secrecy device 63 in the transmitting circuit and to temporarily open the line LRR from the radio receiver during the transmission of outgoing speech. Detector amplifiers 88 and 67 are alternately energized in response to outgoing and in coming speech, respectively, to control the connection and disconnection of the secrecy device and also to prevent echoes and singing in the radio circuit. These functions, however, formno part ofthe invention and W111 not be dlscussed further. when the converher plug GP from the jack 5, thereby releasing relay 6, relay 6 releases relay 7 which in turn releases relay 42, relay 42 in turn releases relay 43, relay. 43 released reconnects the bridged ringing relay 44 across the line and removes battery from conductor 31 to release busy signal 30. Busy signal 29 remains operated under control of relay 24 which indicates at this time that the radio circuit is arranged for transmission to Rio de J aneiro. Under this condition busy signal 30 is unoperated toindicate that the circuit to Rio de aneiro is not busy. Service lamp 36 will be lighted to indicate that the sation is completed the operator will remove transmitter is connected to the Rio de J aneiro remain operated under control of relay .9.

I ncomz'ng ring It will now be assumed thatwith the circuit in condition for transmitting to Rio de Janeiro but with the switchboard plugs removed froin-the jacks, the Rio de Janeiro operator rings over the radio channel, which signals are received and translated in the receiver155 and pass through the amplifier 106, operated contacts of relay 27, and over conductors and 111, normal contacts of relay 80,,contacts of jack 76, normal contacts of relay 79 to'ring-up relay 112 which operates and connects ground to operate relays 75 and 78. Relay 78 operated again opens the transmission circuit and connects terminating resistances 83 and 84 across the two ends of the line. Relay 75 operated connects 20 cycle ringing current through contacts of jack 74 to the two-wire line extending to the switchboard, where it operates the bridged ringing relay 44 whichlocks up under control of relays 43 and 113. Relay 44 operated operates relay 114 in an obvious circuit. Re-

lay 114 operated connects battery to conduc tor 31 to operate busy signal 30 and also connects battery to lead 32 to light the call lamp 33 as an indication to the operator that Rio de Janeiro is ringing on .the circuit.

' When the operator answers by inserting the plug of her cord circuit into'jack 5,relays 6,

7 and 42 operate as previously described. Re-

lay 42 operates relay 43 which relay in operatin opens the holding circuit for relays 44 and 114 which relays "release and extinguish call lamp 33. Busy signal 30, however, remains operated as previously explained by the operation of relay 43. The conversation may now be carried on as previously described between the New York and Rio de Janeiro operators.

In'case the Buenos Aires operator rings while the radio circuit is arranged for transmission to Rio de Janeiro the incoming signals will be translated in the receiver 150 and applied to the line LRB through amplifier 115, operated contacts of relay 27, contacts of jack 116 and the winding of ring-up radio receiver not connected to the toll circuit. I When an operator inserts the plug of her cord circuit into jack 52 to monitor on the receiver over which a ringing signal has just been received, battery from the sleeve of the cord'circuit passes through the sleeve conductor of jack 52, contacts of relay 121 and able to talk with the distant calling station. She is, however, ab e'to listen on the circuitv and in practice a distant call operator will be instructed to rcpeat'any desired message two or three times,which will usually be heard by the New York monitoring operator and in this manner she can very often have the next call ready to be completed when the transmitter circuit is available.

In case the transmitter is idle and a call is received over the monitoring circuit to light lamp 122 which in the case used as an example is from Buenos Aires, the operator will first see that the plug is removed from-the Rio de Janeiro jack 5 and she can then, after having plugged into jack 52 and extinguished the monitoring call lamp 122, plug into the regular Buenos Aires jack123, whereupon battery from the sleeve of the operators cord circuit operates relay 124, thereby closing an obvious circuit for ,the operation of relay 125. Relay 125 operated connects ground from contacts of relay 7 to the battery side of the winding of relay 9 which relay releases as a result of having ground on both ends of its winding. Relay 125 operated also connects battery through its top contacts to open contacts 126 of relay 26 which is now 129. The release of relay 13 also closes the contacts 130 to complete an energizing circuit for relay 18 which may be traced from battery, contacts 131 of relay 20, contacts 130 of relay 13 and winding of relay 18 to ground. Relay 18 closes the power circuit to operate motor 16 which rotates in the direc' tion determined by the energized direct control lead 129 to rotate the antenna switch arms 1, 2 and 3 from right to left. When contact arm 3 engages its left-hand contact, ground is connected to short-circuit relay 20 which releases and opens the circuit for relay 18 to stop the motor. The release of relay 20 also substitutes positive for negative battery previously supplied to conductor 21 which releases negatively polarized relay 22 and operates positively polarized relay 132. Relay 132 operated short-circuits the winding of relay 23, which releases. Relay 23 1eleased removes ground from conductor 148 thereby releasing relays 24, 25, 26, 27 and 28. Relay '24 released connects battery through its contacts 61'to busy signal 30 which operates and connects busy signal 29 to lead 31. Relay 25 released connects ground on lead 45 through to the winding of relay 39, which reoperates. Relay 25 in releasing also transfers lead 35 from lamp 36 to lamp 4 and transfers lead 32 from lamp 33 to lamp 34. Relay 39 reoperated connects battery to lead 35 and lamp 4 in a circuit which may be traced from battery, operated contacts of relay 113,

operated contacts of relay 39, lead 35, normal conta'ctsof relay 25 and through lamp to ground. Lamp 4 lights as an indication to the operator that the Buenos Aires antenna system has been connected to the radio transmitter and the Buenos Aires receiver has been connected'to the line LR. Relay 39 reoperated also relight-s the service lamp 141 at the control operators position. Relay 26 released closes its contacts 126 to operate relay 421F011} battery in acircuit which may be traced from operated contacts of relay 125, contacts 126 of relay 26 and the winding of relay 42 to ground. Relay 42 operated operates relay 43 in an obvious circuit. Relay 43 operated opens" the circuit to the bridged ringing relay 44 and connects battery to lead feb 5 Aires or Rio de aneiro links, i. e., prevent 1 ,915, sss

31 which operates busy signal 29, through normal contacts of relay24; relay 27 released transfers the transmission line LRB fromthe monitoring line LRM to the receiving line LR and also transfers the transmission line LRR from the receiving line LR to the monitoring line LRM. This connects the Buenos Aires radio receiver through to the receiving line and the Rio de J aneiro receiver through to the monitoring line in a manner similar to that described before when the Rio de Jan eiro receiver was connected through to the receiving line and the Buenos Aires receiver was connected through to .the monitoring extinguishes' line; Relay 28 released lamp 59 and lights lamp 58 in an obvious circuit to indicate to 1 the control operator that the circuit is now arranged for transmission between New York and Buenos Aires. Relay 28 released also transfers privacy cut-out control conductor 68' from conductor 7 Q to conductor 69 and privacy control conductor 71 from conductor69 to conducto1'7O.-- A circuit is now arranged for transmission between 'Buenos Aires and blew York in a manner similar to that previously explained for transmission between Rio de J aneiro and New York. {Received or transmittedringing signals and received and transmitted speech signals. operate the circuit exactly the same as previously described .When the circuit was arranged for transmission toBio delanelro.

S It will be'underst ood-that the so-called controlor technical operator who mayor may not be-located in the same building as incoming signalsfrom either of the distant radio'stationsfrom being received and also to prevent the New York toll operator from gaining, control of either of the radio transmitting circuits. This function is performed by cut-out keys 135 and 136, key 135 serving- I to disable the Buenos Aires receiver and prevent'theNewYork operator from connecting the transmitter to the BuenosAires transmitting antenna, and key- 136 serving to dlsable the Rio de 'Janeiro receiver and prevent the NewYork toll operator from connecting the transmitterjto the Rio de Jane ro transmitting antenna. In case the control opera .tor desires to take the circuit away from the operator who may be in communicat on w th either Buenos Aires or R10 de Janeiro, keys 137 and 138 are provided. Operation of key 137 functions'to shift the transmittertothe Rio de Janeiro transmitting antenna in case .circuit;

the operator is talking with Buenos Aires. Operation of key 138 transfers the transmit- -terto the BuenosAires transmitting antenna in case a conversational connection has been established between the toll operator and Rio de Janeiro. Itwill be noted that operation of key 137 or 138 performs the same function as the insertion of the plug GP of a toll cord into elther Jack 5 or 123, i. e., they control the operatlon or release of the switch control relay 9. Keys 137 and 138 are not operated unless the control operator desires to transfer the transmitter from one transmitting. antenna to the other. If the control operator desires to take control of'the circuit but does not Wish to transfer the transmitter from one antenna to the other, it is only necessary for him to operate his-talk key 139 which causes the following operations to take place.

lalk key 139 operated opens the circuit of relay .140 and 113 which are normally operated. Relay 140 released extinguishes the service lamp 141. Relay 113 released removes battery from service lamp 4 or 36 depending upon which radio receiver and transmitting antenna are connected to the transmission Relay ll3 released also connects battery overload 31 to operate either busy signal 29 or 30 depending upon. which transmitting antenna or radio receiver is connected to the transmission system. This indicates to the switchboard operator that neither the radio circuit to Buenos Aires nor Rio de J aneiro is availablefor service. Operation of the control operators talk key 139 also connects. the tip. and. ringconductors of the two-wire transmission circuit into his telephone set circuit 153. By means of key 73 the control operator is able to split the circuit and talk in either direction, i. -e., toward the switchboard or toward the radio circuit. The operation of key 73 to the right connects the radio side of the transmission circuit to the operators telephone set 153 and bridges ring-up relay 142 across the tip and ring of the transmission circuit to the switchboard. This enables the control operator to talk on the radio circuit and if the switch-v board operator rings on the circuit, ring-uprelay 142 will operate and lock up, fromv ground through contacts 143 of key 73 and 5 also operates relay 144 which looks up under control of key73. Relay 144 operated lights the call lamp. 145 at the control operators position as an indication that the Switch board operator wishes to originate a call.

When key 7 3'operates to the left thecontrol operator'is enabled to talk toward the switchboard and ring-up relay '146 is brldged across the transmission circuitfrom the ra- '7 die receiver. If a ringing signal is received over the 1 radio circult under this condition relay 146 operates and locks up from ground through contacts 147 of key 73 and operates relay 144 as b eit'or'e. Relay 144 operated lights lamp 145 as an indication to the con trol operator that a ringing signal has been received over the radio circuit.

What is claimed is:

1. In a radio telephone system, a radio transmitter, a first transmitting antenna directive in apredetermined direction, a second transmitting antenna directive in a predetermined other direction, switching means for connecting the transmitter to either of the antennae, a telephone switchboard, a line extending between said switchboard and said transmitter adapted to control the transmitter, two jacks at the switchboard for making connection with said line, an operators.

cord and plug for making connection with either of said jacks and means selectively and automatically responsive to such connection to actuatesaid antenna-switching means to switch the transmitter into connection with one or the other of said antennae depending on the jack connected to.

2. In a radio telephone system, a radio transmitter, afirst transmitting antenna directive in a predetermined direction, a second transmitting antenna directive in a pre determined other direction, switching means for connecting the transmitter to either of the antennae, a telephone switchboard, a line for controlling said transmitter extending between said switchboard and said transmitter having two terminals at the switchboard,a link circuit at theswitchboard for connecting to one or the other of said line terminals and means selectively and automatic'ally operable, responsive to connection of said link to one or the other of said terminals to actuate said antenna-switching means-to switch said transmitter into connection with one or the other of said antennae depending on which line terminal said link is connected to.

3(Ii1 a radio telephone system, a radio transmitter, a first transmitting antenna directivein' a predetermined direction, a sec-i 0nd transmitting antenna directive in a predetermined other dlrectlon, swltching means 'for connecting the transmitter to either of the antennae, a telephone switchboard, a line extending between said switchboard and said transmitter adapted 'to control the transmitter, two jacks at the switchboard making connection with said line, an operators cord and plug for making connection with either of said jacks, means selectively and automatically responsive to such. connection to actuate said antenna-switching means to switch the transmitter into connection with one or the other of said antennae depending on -the jack connected to, a signal device 38800121366. with eachofsaid acks and means operated ,When sald swltchlng function has been accomplished to operate the signal associated with the jack connected to.

way communication circuit, a plurality of two-way communication circuits remote therefrom, a radio transmitter,a plurality of dlrectlve transmitting antennae each adapted for transmission to a respective one of said remote two-way circuits, a plurality'of directive receiving antennae each adapted for communicationwith a respective one of said remote two-way communication circuits and means associated with said first-mentioned communication circuit for connecting said circuit through said radio transmitter with a desired one of said directive transmitting antennae and for connecting said circuit with a corresponding receiving antenna;

6. In a two-way radiotelephone system, a plurality of distant radio stations each comprising a transmitting and a receiving antenna, a near radlo station comprismg a sep-' .arate receiving system for each of'the distant transmitting antennae, and a separate directional transmitting antenna for each of the distant receiving antennae'and directed to transmit only to itscorresponding distant receiving antenna, a single radio transmitting circuit for said plurality of directional antennae, switching means for connecting the transmitting circuit to any once)? the directional antennae, a telephone switchboard, a line connecting said switchboard and transmitting circuit for controlling said circuit, said linetermin'atlng in the switchboard ina plurality of jack terminals, one for each directional antenna, an operators cord and plug for making connection to said line through any one of said jacks, means selectively and automatically responsive to such a connection to actuate said switching 'ineans to connect a particular one of said directional antennae to said transmitting circuit depending on the 7 jack selected andmeans automatically actuated when a particular directional antenna is connected to the transmittingcircuit to connect the receiving'antenna at the near station, corresponding to the distant transmitting antenna toward whose corresponding receiving antenna the switched directional antenna is directed, to said line extending to the switchboard.

7. In a radio telephone system, a plurality of directive radio receiving systems, a tele- 7 phone switchboard connected by means of phone switchboard, a switching point common to said receiving systems,'a line extending between said switching point and switchboard, means at said switching point for interchangeably connecting any one of said receiving system to said line, a multiple appearance of said line at-said switchboard for each receiving system, and means selectively and automatically responsive to seizure of said line for use at any one of its switchboard appearances to cause, said switching means to connect a predetermined one of said receiving systems to said line depending upon the line appearance seized.

8. 1n a radio telephone system, two differently directive transmitting antennae, a

transmitter, V a corresponding receiving system for each of said antennae, means for switching the transmitter into connection with one or the other of said antennae, a telea line to said transmitter, multiple appearances of said line at the switchboard for making connection therewith, means selectively and automatically operated, dependswitching the transmitter into connection with one or the other of said antennae, a teletolthe ing the actuation of said switching device in a certain manner to cause said transmitter to be connected with the transmitting antennae corresponding to the jack employed in seizing the line.

In witness whereofiwe hereunto subscribe our names, this 14th day of August, 1931.

HAROLD PRUDEN. CHARLES C. -TA YLOR.

phone switchboardconnected by means of a line to saidtransmitter, amonitoring circuit, multiple appearance of said line at the I switchboard for Vmaking connection therewith, means selectivelyv and automatically operated, depending upon the line appearance connected with, to controlthe switch-' ing of said transmitter to one or the other of said antennae 1n a predetermined manner,

and switching means actuated'in response to the operation of said antenna-switch to 0011 meet the recclvlngsystem, corresponding to the switched antenna, to thellne, and to connect the other receiving system to the monitoring circuit,

10. In a radio telephone system, two transmitting antennae, a radio transmitter terminating in a switching device, said switching device having a contact for each of said transmitting antennae, a telephone switchboard connected by means of a line to said transmitter,*said line terminating at said switchboard intwo jacks, each jack corresponding to one of'said transmitting antennae, and means responsive to the seizure of said line at said switchboard for'efiect- 

